The protocol is designed to test the following hypotheses: (1) many types of movement disorders result from mitochondrial DNA mutations in oxidative phosphorylation (OXPHOS), and (2) the clinical symptoms may respond to coenzyme Q10, a drug that may enhance OXPHOS electron transport. Six subjects referred from out of state have undergone extensive evaluation of their movement disorders. The study is part of a large NIH grant, and will be ongoing for the next 4 years.